This invention relates to a method of concentrating the protein content of oilseed meal. More specifically, this invention outlines a new method of achieving higher protein concentration from a variety of protein sources derived from oilseed meals.
As the world population increases, the need for protein is becoming more important as a basic nutritional requirement. The requirements for both protein quantity and quality are well known in the animal and human diet field. Oilseed meals have long been known to be a source of nutritional protein materials. For instance, because of its low cost and high nutritional value, especially in essential protein, it is a generally recognized fact that the soybean is one of the best and cheapest sources of food energy in terms of calories per unit cost of production. The greatest obstacle to the general use of soybeans as a source of human food products is the bitter, beany taste and objectionable odor and color of such products when prepared by prior art methods. Another objection to soybeam food products is their poor keeping qualities and their tendency to become rancid in ordinary storage. In spite of these problems the soybeam has been an important source of food to the Asiatic peoples for many centuries.
Cottonseed flour has been used as a food source for a long time. However, its use has been limited because of the chrome color it imparts to the foods to which it is added and the somewhat bitter flavor of the product, attributable to the inactivated gossypol pigment, and had generally been eliminated from consideration as a protein source for high protein foods. However, recent developments, such as the production of a bland light-colored flour from glandless cottonseed and the development of a low cost process for separating gossypol pigments glands from the protein-containing part of the cottonseed, have made it possible for cottonseed protein to be used in high protein foods.
Other oilseed meals such as sunflower, peanut, safflower, sesame, and rapeseed are also becoming commercially important as new methods of propagation and cultivation yield better seed which are available as potential protein sources.
One known method for increasing the protein content of oilseed meals comprises fine grinding and air classification of the oilseed meal. "Fractionating Corn, Sorghum and Soy Flours by Fine Grinding and Air classification", by V. F. Pfeiffer, A. C. Stringfellow, and E. L. Griffin, Jr., American Miller and Processor, August 1960, pages 11-13, 24, shows that soy flour can be concentrated to a certain extent by passing it through an air classifier and taking off the fines fraction. Water-washing and alcohol-washing are also known methods for producing protein isolates from oilseed meals. U.S. Pat. No. 2,881,076, "Proteinaceous Soy Composition and Method of Preparing" by Louis Sair, patented Apr. 7, 1959, discloses a process for treating defatted soybean material with water at pH 4.0 to 4.8 to produce a high-yield soy product. "Alcohol WAshing of Soybean Protein" by A. C. Eldrige, W. J. Wolf, A. M. Nash, and A. K. Smith, Agricultural and Food Chemistry, July-August 1963, pp. 323-328, discloses alcohol washing of soybean protein to increase the concentration and improve the flavor of the protein. These references do not disclose the combination of air classification and water-washing or alcohol-washing to produce a highly concentrated protein product.
It is therefore an object of this invention to produce a highly concentrated protein supplement derived from oilseeds, adaptable for use in food products. Another object of this invention is to provide a procedure for concentrating oilseed protein. Additional objects, not specifically set forth herein, will be readily apparent to those skilled in the art from the detailed description of the invention which follows.